Authorities around the world ramped up security at transit hubs, stadiums and national landmarks after the Boston Marathon bombings.

In Washington, DC, the Secret Service expanded its security perimeter around the White House. Washington police ordered all day-shift cops to remain on duty during the evening rush hour.

New Jersey Transit deployed extra cops to patrol trains and buses.

In Los Angeles, cops were in a “heightened state of vigilance” and added patrols at that city’s three major airports. Security also was ramped up for last night’s Los Angeles Dodger game, and LAPD cops were told to pay extra attention to large crowds at Dodger Stadium.

California activated its statewide threat-assessment system within hours of the bombings, with officials in San Francisco, Los Angeles, Orange County, San Diego and Sacramento reviewing information about any possible threats, said Kelly Huston, assistant secretary of the California Emergency Management System.

Around the country, flights bound for Boston’s Logan Airport were temporarily kept on the ground because federal authorities set up a no-fly-zone around the region.

And in London, police say they are reviewing security plans for the marathon scheduled for there Sunday as well as for tomorrow’s funeral of former Prime Minister Margaret Thatcher.